Surface reaction probability during fast deposition of hydrogenated amorphous silicon with a remote silane plasma

The surface reaction probability beta in a remote Ar-H-2-SiH4 plasma used f or high growth rate deposition of hydrogenated amorphous silicon (a-Si:H) h as been investigated by a technique proposed by D. A. Doughty [J. Appl. Phy s. 67, 6220 (1990)]. Reactive species from the plasma are trapped in a well , created by two substrates with a small slit in the upper substrate. The d istribution of amount of film deposited on both substrates yields informati on on the compound value of the surface reaction probability, which depends on the species entering the well. The surface reaction probability decreas es from a value within the range of 0.45-0.50 in a highly dissociated plasm a to 0.33 +/- 0.05 in a plasma with similar to 12% SiH4 depletion. This cor responds to a shift from a plasma with a significant production of silane r adicals with a high (surface) reactivity (SiHx,x < 3) to a plasma where SiH 3 is dominant. This has also been corroborated by Monte Carlo simulations. The decrease in surface reaction probability is in line with an improving a -Si:H film quality. Furthermore, the influence of the substrate temperature has been investigated. (C) 2000 American Institute of Physics. [S0021-8979 (00)01307-4].